1. Field of the Invention
The present invention relates to variable resistors, and in particular, it relates to a variable resistor mounted within another variable resistor to provide a compact controller for use in a device, such as a hearing aid.
2. Description of the Prior Art
Great efforts have been made to reduce the size of hearing aids. Two of the major components of a hearing aid include a potentiometer to control volume and a trimmer control to adjust low frequency. Each of these controls are variable resistors which have in the past been mounted separately within the hearing aid. Both controls have to be accessible to the user since they are used on a frequent basis to adjust the volume and the low frequency of the hearing aid. Typically, both controls are mounted on the outer surface of the hearing aid which requires valuable space.
The mounting of variable resistors in coaxial relationship is well known. The following patents provide examples of coaxially mounted variable resistors:
______________________________________ Inventor Patent No. ______________________________________ VanBenthuysen et al 4,105,988 Budd et al 2,883,500 Puerner 3,918,022 Matsui et al 3,913,059 Urwin 3,697,921 Kent 3,597,717 Matsui et al 4,353,053 ______________________________________
However, the above-listed patents describe arrangements which would not be practical or suitable for use in a device such as in a hearing aid.